This specification covers reusable glass serological pipets used for measuring volumes of liquid. The pipets may be classified into three styles according to operational set-up and should be made with approved glass materials. Each pipet should be straight, of one-piece construction, and properly calibrated. All products should conform to the required dimension of delivery tips, zero gradation line position, dimensions and outflow times, graduation markings, color coding, identification markings, and workmanship.